Interspecific hybrid dogwood tree designated &#39;kf1-1&#39;

ABSTRACT

An F 1  interspecific hybrid of  Cornus kousa×C. florida  that is distinguished by its large bracts, a compact and dense attitude, wider than tall, and a flowering habit in the middle of the blooming season for the commercially available cultivars of  Cornus kousa×C. florida.  The cultivar has a high level of winter hardiness, and is highly resistant to dogwood anthracnose and the common dogwood borer.

BOTANICAL DESIGNATION

F₁ interspecific hybrid of Cornus kousa×C. florida

VARIETY DENOMINATION

‘KF1-1’

BACKGROUND OF THE INVENTION

This new cultivar is the product of a long standing detailed program ofinterspecific hybridization and selection of dogwoods, in this instancea controlled cross of an F₁ interspecific hybrid of a Cornus kousa×C.florida. The purpose of the program was to develop new and superiorcultivars of large-bracted dogwoods. The seed parent of this newcultivar is an unnamed seedling of unknown origin of Cornus kousa andthe pollen parent is an unnamed seedling of unknown origin of Cornusflorida. The progeny were carefully retained and characteristicsanalyzed for their differences and outstanding value as potentialcommercial varieties or cultivars.

We have selected the particular seedling hereof from certain progenygrown in a cultivated area and, as a result, have in turn caused thesame to be asexually reproduced by grafting. The reproduction and actualgrowth and selection of the new cultivar took place in the vicinity ofNew Brunswick, N.J. The claimed cultivar is stable and reproducible trueto type in successive generations of asexual reproduction.

As will be understood from the detailed description of the inventionwhich appears hereinafter, the new cultivar is in fact outstanding andreadily identified as being such. With the foregoing in mind, thedescription which follows will be understood as clearly defining the newcultivar, the desirable characteristics of which are the result of sucha program as has been heretofore suggested.

SUMMARY OF THE INVENTION

The variety was originated in a cultivated field at New Brunswick,Middlesex County, N.J. 08901. This seedling resulted from a controlledcross made in June of 1968.

The seedling which became this new variety germinated in February of1969, was transplanted to progressively larger containers, wastransplanted to the field in June 1972 at said horticulture farm inNorth Brunswick, N.J. Two cuttings were taken from this originalseedling in August of 1971, were successfully rooted and weresubsequently field planted at the horticulture farm in June of 1973 forfurther observation along with the original seedling.

The dogwood tree of the present invention is asexually propagated bygrafting (usually T-budding or chip-budding) or by softwood cuttings. Itis distinguished from the other 6 patented commercially availablecultivars of Cornus kousa×C. florida in the following respects:

Aurora® U.S. Plant Pat. No. 7,205 ‘Rutban’ has bracts that are rounded,heavily overlapping, and velvety textured whereas the bracts of ‘KF1-1’are not. Aurora® typically blooms about 2 days after ‘KF1-1’.

‘KF1-1’ is more compact and dense than Celestial® U.S. Plant Pat. No.7,204 ‘Rutdan’ and is wider than tall whereas Celestial® is taller thanwide. ‘KF1-1’ blooms a day or two after Celestial®.

Constellation® U.S. Plant Pat. No. 7,210 ‘Rutcan; Stardust® U.S. PlantPat. No. 7,206 ‘Rutfan’; and Ruth Ellen® U.S. Plant Pat. No. 7,732‘Rutlan’ all have flower heads with floral bracts that are distinctlyseparate with no overlap of adjacent floral bracts. They also flowerearlier in the season than ‘KF1-1’. Further Constellation® is morevigorous and become much larger than ‘KF1-1’. Stardust® and Ruth Ellen®grow very low to the ground as a dense hedge with Stardust® being muchsmaller than and not as wide as Ruth Ellen®.

Stellar Pink® U.S. Plant Pat. No. 7,207 ‘Rutgan’ has pink rather thanwhite floral bracts. It blooms after ‘KF1-1’.

BRIEF DESCRIPTION OF THE DRAWINGS

This new cultivar of dogwood is illustrated by the accompanyingdigitized photographic drawings, depicting the plant by the bestpossible color representation using color photography. All colorreferences below are measured against The Royal Horticultural Society(RHS) Colour Chart. Colors are approximate as color depends onhorticultural practices, such as light level and fertilization rate,among others.

FIG. 1 shows a dogwood tree of the present invention after 29 growingseasons; and

FIG. 2 shows several flower heads of the tree shown in FIG. 1 taken atthe time of floral display, and indicates the color and shape of thefloral bracts.

BOTANICAL DESCRIPTION OF THE INVENTION

-   Form: Tree.-   Growth habit: Dense tree branched low to ground with upright    branches which form a rounded, but spreading, head. Very vigorous,    but compact, and wider than tall.    -   -   Height.—6.7 meters at 36 years.        -   Spread.—7.84 meters at 36 years.-   Plant vigor: Plants of this new variety are more vigorous than    plants of current varieties of C. kousa or C. florida.-   Cold hardiness: The original seedling, and two cutting-grown    propagules thereof, have suffered no winter injury during the 33 and    31 winters since 1971 and 1973, respectively, that the plant    cuttings have been under test in the field at New Brunswick, N.J. in    USDA Plant Hardiness Map Zone 6a (−5° to −10° F.).-   Resistance to insects and diseases: No evidence of insect or disease    problems have been observed on the original seedling, or its    propagules, in the many years the plants have been under test in New    Jersey, and Tennessee. No powdery mildew observed on the plants    grown in New Jersey and Tennessee, but some powdery mildew was    observed on plants of ‘KF1-1’ under test in Oregon. No evidence of    susceptibility to Dogwood anthracnose or common dogwood borer.-   Trunk: Circumference of the trunk at 10 cms. above the soil level    was 1.24 m after 36 growing seasons.    -   -   Texture.—Smooth when young, but becoming shaggy with age as            then exhibits heavily exfoliating bark.        -   Color of exfoliating bark.—A mottled pattern of areas            closest to 197A and 197B Greyed-Green Group and areas            closest to 199B and 199D Greyed-Brown Group.        -   Color of smooth trunk under exfoliated bark.—is closest to            165C Greyed-Orange Group.        -   Lenticels.—Imperceptible on exfoliating bark. Three year            branches sandpaper rough due to high number (average            69-range 56-88 per cm²). Size of lenticels 0.5-0.7 mm long            by 0.3 mm-0.4 mm wide.-   Branches:    -   -   Color.—Closest to 197A Greyed-Green Group.        -   Texture.—Smooth on young branches but becoming sandpaper            rough with age.        -   Crotch angle.—35-55° for large, major branches but 45-70°            for subsequent smaller branches.

FOLIAGE

-   Leaf arrangement: opposite.-   Leaf size: Blade.    -   -   Average length.—13.6 cm (range 11.8-16.8).        -   Average width.—6.9 cm (range 5.9-8.3), the widest point            being a little more than half-way down from the tip.        -   Shape.—Ovate/elliptic.        -   Tip.—Apiculate.        -   Base.—Attenuate.        -   No. of pairs of veins.—Principally 5.        -   Margin.—Moderately wavy.        -   Texture.—Adaxial is quite smooth, although it has many            minute whitish hairs. The abaxial surface is slightly fuzzy            due to many minute, whitish hairs on the blade and tufts of            longer, thin hairs along the midrib and the side veins.        -   Quantity.—Many, densely foliaged.-   Coloration: Solid.    -   -   Mature leaf color-adaxial.—Closest to 139A, Green Group, but            Greener. — abaxial: 139C, Green Group.        -   Petiole.—Closest to 144B Yellow-Green Group.        -   Immature leaf color-adaxial.—Closest to but darker than 144A            Yellow-Green.-   Group. abaxial: Color in between 138B and 138C Green Group.    -   -   Petiole.—Closest to 146C Yellow-Green Group.-   Autumn foliage color (mid-October), New Brunswick, N.J.    -   -   Adaxial surface.—approximately 85 percent of leaves 137A            Green Group with the other leaves predominantly green but            mottled with other colors: mostly 187A Greyed-Purple Groups,            183A Greyed-Purple Group, 53A Red Group, 46A Red Group, 43A            Red Group, and 9A Yellow Group. The color of the midrib from            the petiole to the base of the uppermost pair of side veins            shows a little yellow streak closest to 145 Yellow-Green            Group.        -   Abaxial surface.—136D Green Group.

Leaf color is clearly dependent on many environment factors such as soiltype, available water and nutrients, exposure to sun, air temperatureand day length. Thus, autumn foliage color may vary from one area toanother and from year to year. Some years, fall coloration ispredominantly 187A and 187B Greyed-Purple Group.

-   -   -   Petiole.—Color at New Brunswick, N.J.        -   May.—Closest to 146C Yellow-Green Group.        -   October.—145A Yellow-Green Group.

INFLORESCENCE

-   Location where observations were made: New Brunswick, N.J.-   Type of inflorescence.—Flower head. Dense, rounded mound.-   Peduncle size (in mid-June at time of flowering (n=20 measurements):    -   -   Average length.—3.84 cm (range=2.8 cm-5.0 cm).        -   Average width.—1.85 mm (range=1.5 cm-2.0 cm).

At the time of flowering, the peduncle length of the C. kousa parentaverages about 7.3 cm and those of the C. florida parent average about2.0 cm. Absolute peduncle length will vary slightly from year to yearbut the relative peduncle length among the hybrid ‘KF1-1’ and the twoparents should remain consistent.

FLORAL BRACTS

-   Number: Four (two opposing pairs).

Size of floral bracts at time of floral period; mid-June. TABLE 1 nAverage length Average width Inner, floral bracts 50 5.36 cm 4.25 cm 25Involucral spread: 10.91 cm

TABLE 2 n Average length Average width Outer 50 4.58 cm 4.67 floralbracts 25 Involucral spread: 9.35 cmWhere n = number of measurementsThe average length of the inner bracts is longer than the average lengthof the outer bracts. The average width of the inner bracts is less thanthe average width of the outer bracts. Bract length and width will varyslightly from year to year but the inner bracts will be longer andnarrower than the outer bracts each year. This is consistent with therelative length and width of the inner and outer bracts of all of theother patented F₁ interspecific hybrids of C. kousa×C. florida in thetrade today.

-   Shape: The floral bracts are basically obovate with a broad    acuminate tip and a truncate end with a small, abruptly acute tip at    the center. Similar to the floral bracts of Celestial® but    distinctly different from those of the other five interspecific    hybrids noted above.-   Color: At peak of floral display: (approximately May 19):    -   -   Adaxial.—closest to and in between 4C and 4D Yellow Group.        -   Abaxial.—closest to 4D Yellow Group.-   Approximately May 27:    -   -   Adaxial.—closest to 4D Yellow Group but much whiter.        -   Abaxial.—closest to 155D White Group.-   Flower description: Very floriferous. Single flowers arranged in    compact, dense heads. (convex mound on flat base, 6.36 mm high and    9.38 mm wide). No observed fragrance. Flowers not persistent. Floral    display of the involucral bracts last about 14-19 days, depending on    weather conditions.-   Flowering habit: Anthesis of the tiny, relatively inconspicuous true    flowers generally begins a few days after onset of the ornamental    display of the large floral bracts. The period of floral display    (floral bracts) is intermediate to that of plants of the parent    species; i.e., occurs in early to mid-May, commencing about two to    four days after completion of the floral display of most plants    of C. florida and ending about the time the floral display of early    flowering plants of C. kousa begins.-   Number of true flowers per flower head: The average number of true    flowers per flower head in the hybrid ‘KF1-1’ is 36.3, (based on    n=30 measurements), and is intermediate to that for the C. kousa    parent (average=49) and that for the C. florida parent (34.5).

REPRODUCTIVE ORGANS

-   Stamens: Number per flower: 4.    -   -   Filament.—Length — approximately 2.75 mm (n=4) Width —            approximately 0.28 mm (n=4) Color — 155B White Group.        -   Anther.—Length — approximately 0.4 mm (n=4) Width —            approximately 0.81 mm (n=4) Color — 162A Greyed-Yellow            Group.        -   Pollen.—somewhat brownish-yellow.-   Pistil:    -   -   Style.—Height — approximately 1.94 mm (n=4) Width —            approximately 0.3 mm (n=4) Color — 144B Yellow-Green Group.        -   Stigma.—Height — approximately 0.25 mm (n=4) Width —            approximately 0.5 mm (n=4) Color — 162A Greyed-Yellow Group.-   All figures are based on an average of the 4 measurements.

FRIUT

No fruit develops as the plants are sterile. The vast majority of flowerheads drop after flowering.

1. A new and distinct cultivar of dogwood tree comprising an F₁interspecific hybrid of Cornus kousa×C. florida, substantially as hereinshown and described.